Deregulation of the airline industry has resulted in reduced airfares, which when combined with stable fuel prices, has further produced a volume of air travel that has been strongly and steadily increasing in the past decade. This trend is expected to continue unabated over the next two decades. However, airport support infrastructure, has not kept pace with increasing traffic volume, and is expected to lag further in the coming decades. Due to the limited numbers of airport gates, there is a strong motivation for airlines to move to larger aircraft to accommodate increased passenger volume through fewer gates. The need for larger aircraft is particularly critical at major “hub” airports in the “hub and spoke” systems operated by most large airlines in order to maximize passenger flow through their limited airport facilities.
Airlines experience significant logistical and operational problems trying to physically accommodate the increased wingspan, that which characterizes the new stretch derivative and super jumbo aircraft, in airport gates and taxiways designed for smaller aircraft. New aircraft designs are experiencing a modern trend towards increasing wingspan in view of the substantially improved aerodynamic efficiency and payload-range characteristics. The increased wingspan and/or length of larger aircraft will make parking such aircraft next to each other at gates more risky in terms of probability of collision, and will also increase problems related to ground services, arrangements, flows, and congestion. Similarly, the increased wingspan increases the probability of collisions between aircraft taxiing on adjacent taxiways/taxilanes or fixed objects. Finally, the modern trend towards greater aircraft densities operating in and around airports is necessitating greater aircraft maneuvering precision in the airport infrastructure.
Several prior logistical/operational approaches have been considered, which address the problems associated with fitting larger aircraft into airport facilities originally designed for smaller aircraft. One approach to maximizing passenger volume capability at a limited number of airport gates has been to park the largest possible aircraft type that will “fit” at each gate, given the constraining requirements of minimum clearances between the parked aircraft's wingtips and the wingtips of adjacent parked or parking aircraft and between the parked aircraft's aftmost extremity (e.g., tip of tail) and the “parking limit line” which separates the parking area from an adjacent active taxilane. This is a reasonable approach, but is inherently limited in the amount of additional passenger volume it can develop. Airline fleet mix, and more particularly the fleet mix present at each hub complex (i.e., the mix of aircraft actually present simultaneously at a gate constrained hub airport), can reduce the effectiveness of this strategy in increasing passenger volume. Airport terminals with movable (i.e.; apron-drive type) passenger boarding bridges can take advantage of this method to a considerably greater extent than can airport terminals with fixed boarding bridges, because movable bridges can be moved to effectively change the maximum aircraft size accommodatable at each gate.
A second approach has been to reduce the allowable operational clearances between parked aircraft and between a given aircraft and other fixed or moving objects (including other aircraft). An FAA Advisory Circular 150/5300-12 CHG 1, Mar. 14, 1985 specifies minimum clearances to be assumed for airport facilities design and expansion purposes. The specified clearance between a taxiing aircraft's wingtip and a nearest fixed-or-movable object is 32.5 ft. for Group IV airplanes (e.g., 767 or DC-10 class). The FAA does not regulate actual clearances used by airlines in their day-to-day commercial operations. Current airline practice includes examples of wingtip-to-wingtip clearances of as low as 17 ft. between adjacent parked aircraft. An obvious disadvantage of this second approach is that it increases the probability of collisions, and requires increased pilot attention and precision for the taxiing and parking tasks.
A third approach is to alternate large and small aircraft (747's and 737, A320, MD80's) at gates nominally designed for 767/DC-10 size aircraft. While this approach increases the size of the largest accommodatable aircraft, it has a disadvantage in that it may not significantly increase total passenger volume accommodatable. The realization that a combination of 5(qty.)-747's and 5(qty.)-737's may not result in significantly greater passenger volume than 10(qty.) DC-10's, illustrates this phenomenon.
A fourth approach goes beyond reducing allowable clearances between aircraft or alternating large and small aircraft, and instead takes into account the vertical separation between wingtips. For example, a DC-10 could be parked adjacent to a 727 with zero or even negative wingtip separation in a plan view, but with no real wing interference if the 727 wingtip passes under the DC-10 outer wing. Adequate vertical clearances have to be established accounting for the lowest possible ground clearance for the DC-10 wing and the highest possible wingtip location for the 727 (e.g., due to weight, gusts, etc.). However, this approach is disadvantaged in that it requires that airplanes with adequate vertical clearances be alternately parked, and therefore inherently limits gate assignment flexibility, and it aggravates problems of ground service vehicle access and parking.
A fifth approach has been to use angular aircraft parking in combination with carefully designed nonlinear (e.g., curved) taxi-in paths. This enables larger aircraft to park at gates designed for smaller aircraft, with the same level of wingtip-to-nearest-fixed-or-moving-object separations. While this approach is judged to be a viable for increasing the maximum aircraft size accommodatable and therefore total passenger volume accommodatable at space constrained airport gates, the amount of increased airplane wingspan is limited to about 5 to 10%. This approach is further disadvantaged when significant parking angles require modifications to be made to certain boarding bridges (e.g., fixed pedestal bridges) to increase the yaw swivel capability of the boarding bridge head to assure proper sealed mating of the bridge head with the aircraft door. U.S. Pat. No. 3,916,588: Integrated Industrial and Urban Airport Complex with Passenger and Freight Handling Facilities, & U.S. Pat. No. 4,218,034: Industrial and urban airport complex with Special cargo-handling facilities—Both teach an airport configurations that use angled aircraft parking to improve densities.
A sixth approach to increasing aircraft size accommodatable between adjacent parallel airport terminal piers is to replace dual, bidirectional wide-body aircraft taxilanes, with unequal width dual taxilanes, that are bidirectional for narrow-body aircraft (e.g., 737's and 757's) but are only unidirectional (i.e., effectively single lane) for increased span wide-body aircraft. However, this limitation could aggravate ground traffic congestion delays at major hub airports.
A seventh approach is taught by; U.S. Pat. No. 5,381,986“Folding Wing-tip System”; which uses novel folding wingtips to allow large aircraft to be parked in space constrained gates and taxilanes. This clever approach although providing significant airport compatibility benefits, suffers from increased weight, complexity, and cost penalties to the host aircraft.
As will be apparent, variations and combinations of the above-mentioned approaches are also possible. All of the approaches cited above, except for approaches second and seventh, have the disadvantage of not allowing for increased airplane wingspan for dual bidirectional taxilanes between parallel terminal piers.
In addition to logistical and operational methodologies, a considerable amount of ground based, airport infrastructure airplane guidance hardware has been developed to assist the maneuvering of aircrafts around runways, taxilanes and terminal areas:
U.S. Pat. No. 6,362,750: Process and device for automatically supported guidance of aircraft to a parking position—A ground-based video-camera enabled system for providing guidance of aircraft to a parking position;
U.S. Pat. No. 6,324,489: Aircraft identification and docking guidance systems—A laser range finder enabled system for identifying an aircraft approaching a gate;
U.S. Pat. No. 6,282,488: Airport surface movement guidance and control system—A radar-based airport surface movement guidance and control system for display of positions and movements of aircraft, and vehicles around runways, taxiways, and aprons;
U.S. Pat. No. 6,100,964: Method and a system for guiding an aircraft to a docking station—An infrared sensor enabled system for providing detection and guidance of aircraft into parking gates;
U.S. Pat. No. 5,675,661: Aircraft docking system—An optical-laser based aircraft docking and external display system for providing pilots visual cues in response to sensed position;
U.S. Pat. No. 5,574,648: Airport control/management system using GNSS-based methods and equipment for the control of surface and airborne traffic—A GNSS & terrain map enabled system for controlling traffic wherein the aircraft utilize GNSS to calculate trajectory information and in turn communicate to a ground based monitor for updating a 3 dimensional terrain database;
U.S. Pat. No. 5,519,618: Airport surface safety logic—A computer system for tracking, detecting, predicting and management of potential aircraft collisions;
U.S. Pat. No. 5,375,058: Surface detection system for airports—Ground-based infrared scanners sense bar codes mounted on taxiing aircraft in conjunction with a ground-based aircraft position mapping and collision alert system;
U.S. Pat. No. 5,166,746: Aircraft docking guidance system which takes position reference in anti-collision light of aircraft—A CCD enabled aircraft docking system which senses the position of aircraft anti-collision lights and provides external guidance cues to pilots;
U.S. Pat. No. 4,995,102: Scanning method used by laser radar and laser radar for carrying out the method—A laser range finder enabled system for identifying and detecting the presence of aircraft and other traffic on an airfield;
U.S. Pat. No. 4,994,681: Device for detecting the position of a moving body, in particular an aircraft, in a plane—A laser source and camera detector enabled aircraft docking position sensor wherein laser reflections off an approaching aircraft are sensed for calculating position information;
U.S. Pat. No. 4,516,125: Method and apparatus for monitoring vehicle ground movement in the vicinity of an airport—A radar enabled apparatus for monitoring vehicle ground movement in the vicinity of an airport and involves the processing of radar return video signals;
U.S. Pat. No. 3,775,741: AIRCRAFT PARKING SYSTEM and U.S. Pat. No. 4,249,159: Aircraft docking system—These provide illuminator based docking-centerline deviation guidance that require reflective targets to be mounted to said aircraft;
U.S. Pat. No. 3,729,262: OPTICAL LENS DOCKING SYSTEM—An illuminator and lens based docking system so as to generate external visual cues comprising two bars of light that vary in their respective reference in accordance with the displacement of the aircraft.
U.S. Pat. No. 3,674,226: AIRCRAFT PARKING METHOD AND MEANS—A high intensity neon tube illuminator based docking system so as to generate external visual cues that demarcate aircraft parking alignment lines.
U.S. Pat. No. 3,821,697: VISUAL LANDING AND SURFACE GUIDANCE APPARATUS—A multi-illuminator based guidance system that operates similar in principle to an radio frequency (RF) Instrument Landing System (ILS) or Visual Approach Slope Indicator (VASI).
U.S. Pat. No. 4,184,655: Parking guidance system for aircraft—A ground-sensor based aircraft docking system wherein nose wheel position is sensed and displayed externally to pilots;
U.S. Pat. No. 4,015,235: Aircraft parking guidance indicator—A terminal-based optical positioning system for docking an aircraft wherein a positioning target and the phenomenon of optical parallax are used to indicate aircraft centerline deviation and correct stopping position in a parking gate;
Other ground-based systems have been developed that were characterized as providing a significant impact on the ground infrastructure, and are characterized as harnessing classic radio-frequency, electromagnetic or static principles:
U.S. Pat. No. 5,689,273: Aircraft surface navigation system—RF-based, ILS glideslope deviation indicator with taxilane based RF signal generator to provide taxilane centerline guidance;
U.S. Pat. No. 5,027,114: Ground guidance system for airplanes—An inductive loop coil enabled system for detecting aircrafts on taxiways wherein loop coils are buried in a specific section of a taxiway for sensing aircraft based on changes of self-inductances of the loop coils with movement of the airplane;
U.S. Pat. No. 3,662,977: Aircraft taxi guidance system; U.S. Pat. No. 2,574,490 Magnetic blind-landing system—Electro magnetic enabled systems for detecting aircraft taxi centerline deviation relying on buried conductors;
U.S. Pat. No. 3,431,996: Vehicle guidance system; U.S. Pat. No. 3,132,710: Vehicle ground guidance system; U.S. Pat. No. 2,044,852: Electric indicator for comparing field intensities; U.S. Pat. No. 1,968,068: Process and apparatus for measuring the phase difference of electric currents—Electrostatic enabled system systems relying on buried conductors.
Finally aircraft based systems:
U.S. Pat. No. 6,405,975: Airplane ground maneuvering camera system—An autonomous aircraft-based external camera system for aiding pilots in the ground maneuvering of an airplane;
U.S. Pat. No. 3,855,571: AIRCRAFT GROUND TRAFFIC CONTROL SYSTEM—Traffic control system wherein aircraft mounted sound emitters are tracked using taxiway mounted microphones and displayed on a controller's panel in the form of a map.
These systems have comprised a spectrum of technologies from relatively simple optical visual maneuvering cueing devices for pilots, to electro or radio enabled runway centerline deviation indicators; to radar enabled ground traffic situation indicators for terminal control area controllers. Few have been successfully adopted on a wide spread basis due to the costs, complexities of implementation, and unreliable performance in inclimate weather. All are characterised as primarily relying on the pilot to synthesize the correct response in reaction to guidance cues. Further, all are characterised as being a non-intergrated part of the normal pilot-aircraft operational enviroment. What is needed is an aircraft “autotaxi” or “autotiller” system that is integrated into, and makes use of, the recent advances in aircraft systems and airport traffic management technologies.